Many if not most decals are graphics-image-bearing portions (sometimes referred to herein as “product areas,” whether or not they have graphics images thereon) of a removable layer (sometimes referred to herein as a “face layer”) of a laminate. Each such decal laminate typically includes the face layer and a backing layer (or “liner”), the face layer being removably secured to the backing layer by an adhesive. The adhesive is preferential to the face layer, and is used, after removal of the product area(s) from the backing layer, for the adhesive attachment of the product area(s) of the face layer onto the surface intended to be covered—for decorative, signage or any of a multitude of other purposes.
To facilitate production of product areas (decals) in a form ready for use, it is frequently necessary or desirable to pre-remove the area or areas of the face layer which is/are not product areas from the backing layer of the decal laminate. (These non-product areas of the face layer are often referred to herein as “waste areas.”) Such pre-removal of waste areas leaves the product area(s) on the backing layer—ready to be easily peeled away from the backing layer just prior to use. The pre-removal of waste areas of a face layer, sometimes referred to “sheet-weeding,” greatly facilitates the subsequent removal of product areas (decals) just prior to use.
(The pre-removal of waste areas, of course, follows slitting or other severing of the product areas from the waste areas, which occurs while the removable layer to be slit or severed is in place on the backing layer. A highly preferred and advantageous method and apparatus for accurate severing around the product area or areas of the face layer of a decal laminate is disclosed in commonly-owned U.S. patent application Ser. No. 09/678,594, filed Oct. 4, 2000, entitled “Method and Apparatus for Precision Cutting and the Like of Graphics Areas from Sheets,” now U.S. Pat. No. 6,772,661.)
Sheet-weeding is typically carried out by nimble-fingered workers who delicately lift and peel away unused portions of the image-bearing face layer of a decal laminate. This is tedious and time-consuming work. Progress has been made toward automating the sheet-weeding process; despite such efforts, there remains a need for an improved automatic waste-area removal method and apparatus.
Various automated systems have been devised over the years for facilitating sheet-weeding operations. Among these are the systems and concepts disclosed in the following United States patents: U.S. Pat. No. 5,143,576 (Logan); U.S. Pat. No. 5,277,736 (Logan); U.S. Pat. No. 5,026,584 (Logan); U.S. Pat. No. 4,246,058 (Reed); U.S. Pat. No. 4,786,537 (Sasaki); U.S. Pat. No. 5,695,600 (Goin); and U.S. Pat. No. 4,333,781 (Meulenberg). These prior systems each have certain disadvantages or problems, some of which are set forth below.
The computer-controlled systems of the Logan patents use complex adhesive materials including microspheres or microcapsules which, when broken by force application, release strong adhesive to allow an overlay sheet to engage and remove portions of a sheet. Such adhesives can be very expensive, and force-activation can be problematic and difficult in high-speed operations.
The Reed disclosure involves an embossing of areas to be removed in order to weaken their adhesive attachment to the base layer and facilitate removal. However, such embossing tends to be a step which, among other things, may be unacceptable for removal of intricate waste areas or patterns around irregularly shaped decals or product areas.
The Sasaki disclosure involves removal of an overlayer after a separation is caused by radiation treatment of a radiation-responsive composition. This system is complex and believed not to be suitable for many high-speed production operations.
The prior systems and disclosures fall short of offering and delivering simple, effective sheet-weeding which is fully suitable for high-speed decal production and similar waste-area removal operations.